Mixed Selectivity Control Agent Catalyst for Propylene Polymerization
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Solution Overview
Problem
The excessive heat generated during olefin polymerization reactions poses a risk to reactor operability, leading to potential disruptions or shutdowns, as existing catalyst compositions with mixed selectivity control agents do not effectively manage heat levels.
Innovation Solution
A catalyst composition comprising a procatalyst, cocatalyst, and a mixed external electron donor (M-EED) with a specific mole ratio of selectivity control agents and an activity limiting agent, which self-limits the polymerization reaction, reducing heat generation and maintaining high melt flow and stiffness in propylene-based polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If catalyst compositions with mixed selectivity control agents are used to produce high stiffness propylene-based polymers, then polymer stiffness and melt flow are improved, but excessive heat is generated during polymerization leading to reactor disruption or shutdown
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by introducing a specific combination of selectivity control agents (SCAs) including dimethoxysilane, diethoxysilane, triethoxysilane, tetraethoxysilane, trimethoxysilane, diether, dialkoxybenzene, and dimethoxysilane with specific alkyl groups. This parameter change enables the catalyst to produce high stiffness polymer while self-limiting the reaction to prevent excessive heat generation, resolving the contradiction between polymer strength and reactor reliability
Solution Approach 2:
The patent employs a composite catalyst system combining multiple selectivity control agents with specific proportions. This composite approach allows the catalyst to achieve both high polymer stiffness and controlled heat generation, maintaining reactor operability while producing the desired polymer properties
2Productivity
If catalyst compositions with mixed selectivity control agents are used to produce high melt flow propylene-based polymers, then polymer melt flow rate is improved, but excessive heat is generated during polymerization
Solution Approach 1:
The patent modifies the catalyst composition parameters by incorporating specific SCAs in defined proportions, enabling the system to produce high melt flow polymer while self-regulating heat generation through the catalytic system's inherent properties, thus resolving the contradiction between productivity and energy loss
3Productivity
If standard polymerization conditions are used with existing catalyst compositions, then polymer production is maintained, but reactor shutdowns occur due to excessive heat
Solution Approach 1:
The patent introduces a self-limiting catalyst system that provides inherent feedback control on heat generation. The specific SCA combination enables the catalyst to automatically regulate its activity based on reaction conditions, preventing runaway reactions and maintaining stable reactor operation while preserving productivity
Solution Approach 2:
The catalyst system performs self-regulation of its own activity through the inherent properties of the SCA mixture. This self-service mechanism eliminates the need for external intervention to control heat generation, ensuring both continuous production and operational stability without requiring additional control systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The catalyst composition effectively produces propylene-based polymers with high melt flow rates and stiffness while preventing reactor disruptions by self-limiting the polymerization reaction, ensuring stable reactor operation and maintaining polymer properties without the need for visbreaking.
Implementation Method 1
The catalyst composition includes a procataiyst composition, a cocatalyst, and a mixed external electron donor (M-EED). The M-EED includes an activity limiting agent (ALA), a first selectivity control agent (SCA1), a second selectivity control agent (SCA2).
Implementation Method 2
The excessive heat generated during polymerization poses a significant risk to the polymerization reactor operability. Excessive heat generation and/or inadequate heat removal can readily disrupt production and/or shut down the reactor.
Data Source
AI summary
The present disclosure provides a Ziegler-Natta catalyst composition comprising a procatalyst, a cocatalyst and a mixed external electron donor comprising a first selectivity control agent, a second selectivity control agent and an activity limiting agent. A polymerization process incorporating the present catalyst composition produces a high-stiffness propylene-based polymer with a melt flow rate greater than about 50 g/10 min. The polymerization process occurs in a single reactor, utilizing standard hydrogen concentration with no visbreaking.